American trypanosomiasis (Chagas disease) is a protozoan infection caused by the flagellate Trypanosoma (Schizotrypanum) cruzi, widespread in the Americas, and endemic to Central and South America. Chagas disease can be quickly fatal, especially in children, or it can be carried asymptomatically for decades. Between 10-30% of infected people eventually develop severe cardiac or digestive chronic involvement as late manifestations of Chagas disease. These complications are usually fatal. In the Americas, approximately 16-18 million people are estimated to be infected by the parasite. This estimate does not include Mexico and Nicaragua, for which accurate public health data are not available.
Due to recent patterns of urbanization and immigration, Chagas disease is no longer a unique problem for Latin American countries. Estimates a decade ago suggested that approximately 300,000 infected individuals were living in the city of São Paulo, and more than 200,000 in Rio de Janeiro and Buenos Aires. In addition, Chagasic patients with chronic and asymptomatic forms of the disease are immigrating northward to the USA and Canada, and even eastward to Europe. Several years ago it was estimated that around 100,000 infected individuals were already living in the USA, most of them having immigrated from Mexico and Central America. Many of these immigrants are unaware that they have contracted Chagas disease and continue to donate infected blood. Controlling “transfusional” Chagas disease is therefore of paramount importance in preventing infection in the USA and Canada.
Chagas disease may also be transmitted congenitally. Several American families never exposed by travel to endemic areas were congenitally infected by parents or grandparents from Central or South America. Programs in Central and South America are presently engaged in attempting to screen pregnant women and newborns to reduce the rate of congenital chagas.
Presently, no optimal test is available for the diagnosis of chronic-stage Chagas Disease. The most straightforward available method of excluding potentially infected donors from the blood pool is to ask questions about immigration and travel involving Central and South America. These geographic exclusions are somewhat insensitive and subject to the reliability of the potential donor. As a result, a large number of willing and healthy donors are inappropriately excluded, thus contributing to a blood donor shortage in Canada and the US. A quick, accurate, and inexpensive screening test is therefore needed to provide a rapid diagnosis of Chagas disease and to ensure the safety of blood supplies.